Electronic and Magnetic Properties of a Monolayer of VOTPP Molecules Sublimated on Ag(100)

Vanadyl(IV) 5,10,15,20-tetraphenylporphyrin (VOTPP) is an S = 1/2 molecular system with remarkable spin qubit properties. Its structure offers a higher chemical tunability with respect to archetypal molecular qubits, such as vanadyl(IV)Phthalocyanines (VOPc), and a less rigid organic scaffold where peripheral phenyl rings can promote electron decoupling from the substrate. The properties of a VOTPP monolayer on the Ag(100) surface by photoemission spectroscopies and synchrotron radiation are studied. The results indicate that the electronic and spin features of the massive phase are retained in the monolayer. Moreover, X-ray photoelectron spectroscopy revealed the existence of two distinct species characterized by varying strengths of molecule-surface interactions. Like VOPc, these species can be assigned to molecules with the vanadyl group oriented upward or toward the surface. However, in contrast to VOPc, only subtle screening effects are observed in the oxygen-down configuration, suggesting a more pronounced decoupling effect inherent in the VOTPP structure. This opens broader perspectives for investigations focusing on spin characteristics at the single-molecule level.